CLEVELAND — Republican presidential candidate Sen. Marco Rubio (R-FL) participates in the first prime-time presidential debate hosted by FOX News and Facebook at the Quicken Loans Arena August 6, 2015 in Cleveland, Ohio. The top-ten GOP candidates were selected to participate in the debate based on their rank in an average of the five most recent national political polls. (Photo by Chip Somodevilla/Getty Images)

CLEVELAND — The ten candidates invited to the first major debate of Republican presidential hopefuls take the stage at the Quicken Loans Arena in Cleveland, Aug. 6, 2015. From left: Gov. Chris Christie of New Jersey; Sen. Marco Rubio (R-Fla.); Ben Carson, the retired neurosurgeon and political commentator; Gov. Scott Walker of Wisconsin; Donald Trump, the real estate mogul and television personality; Jeb Bush, the former governor of Florida; Mike Huckabee, the former governor of Arkansas; Sen. Ted Cruz (R-Texas); Sen. Rand Paul (R-Ky.); and Gov. John Kasich of Ohio. (Eric Thayer/The New York Times)

CLEVELAND — Ben Carson, the retired neurosurgeon and political commentator, participates in the first Republican presidential primary debate, at the Quicken Loans Arena in Cleveland, Aug. 6, 2015. Looking on is Gov. Scott Walker of Wisconsin. (Eric Thayer/The New York Times)

So much for the notion that Republican presidential front runner Donald Trump might tone down his reality show bombast for his first-ever political debate Thursday night.

Trump wouldn’t rule out a third-party White House bid if he doesn’t win the GOP nomination, shrugged off past bankruptcies by his businesses, said he made political contributions to buy influence and refused to back down from harsh comments about Mexican immigrants.

“If it weren’t for me you wouldn’t even be talking about illegal immigration,” Trump said of the issue that has generated Hispanic outrage and catapulted him to the top of Republican polls.

Rubio, 44, cast himself as a candidate of the future and a product of middle class upbringing, drawing a distinction from the 62-year-old Bush, the scion of a wealthy political dynasty.

“This election better be about the future, not the past,” Rubio said.

“If I’m our nominee, how is Hillary Clinton going to lecture me about living paycheck to paycheck? I was raised paycheck to paycheck. How is she going to lecture me about student loans? I owed over $100,000 just four years ago. If I’m our nominee, we’ll be the party of the future,” Rubio said.

Rubio also took issue with the Common Core education standards favored by Bush. While Bush insisted local governments should set education standards, Rubio claimed the U.S. Department of Education “will not stop with it being a suggestion” and would turn Common Core into a federal mandate.

Before the main event, former Hewlett Packard CEO Carly Fiorina dominated a debate of seven GOP candidates excluded from the main debate by Fox News because of their low polling numbers. Fiorina skewered Republican front runner Trump over his ties to Bill and Hillary Clinton and shifts on abortion, immigration and health care.

Fiorina didn’t name Bush but said the GOP nominee “cannot stumble before he even gets into the ring.” She confirmed after the debate that she was talking about Bush’s recent remark that “I’m not sure we need half a billion dollars for women’s health issues.”

Bush’s comment angered many conservatives because it conflated the debate over Planned Parenthood and its use of aborted fetal tissue with the broader question of women’s health and allowed defensive Democrats to go back on offense.

Asked specifically about Bush in a post-debate interview, Fiorina said: “It’s disappointing. I spent all of last year with a lot of other conservatives pushing back effectively against the ‘War on Women’…It’s really disappointing when a front-runner gives the Democrats an ad and a talking point before he’s even in the ring.”